def is_null(em,cd,pwd):
    import re
    em = em.strip()
    cd = cd.strip()
    pwd = pwd.strip()
    if em:
        e = re.match(r'[a-zA-Z0-9_-]+@[a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)+', em)
        if e:
           if cd:
               if pwd:
                   p = len(pwd)
                   if p<8:
                       return "*密码位数不能小于8*"
                   elif p>16:
                       return "*密码位数不能大于16位*"
                   else:
                       return '1'
               else:
                   return '*密码不能为空*'
           else:
               return "*验证码不能为空*"
        else:
            return "*邮箱格式错误*"
    else:
        return "*邮箱号码不能为*"



if __name__ == '__main__':
    em = "7342332282qq.com"
    cd = "123"
    pwd = "123666655"
    a = is_null(em ,cd,pwd)
    print(type(a))
